Cargo within trucks, unless it substantially fills the space, tends to shift position due to acceleration, deceleration and/or vibration. Typically freight line trucks are not completely filled, thus giving rise to the shifting problem. Vans used for moving typically utilize webbed belts to fix the cargo in space and, since there is usually no need for rearranging the load between the loading location and the ultimate destination, the load remains in a fixed position. However, in trucks where there are relatively frequent stops, with a part of the cargo removed each time, some more convenient form of load securing devices are required.
Extendable bracing bars are well known in the art of load bracing in the trucking industry. Many of the devices designed for this purpose provide for a gross adjustment of length by having an extendable bar, and then the minor adjustment is accomplished by some type of jacking and latching mechanism. Typical of the devices that have been developed are described in U.S. Pat. Numbers: U.S. Pat. No. 1,951,660 issued to H. Klaudt on Mar. 20, 1934; U.S. Pat. No. 4,343,578 issued to B. Barnes on Aug. 10, 1982; U.S. Pat. No. 4,432,678 issued to H. Liebel on Feb. 21, 1984; U.S. Pat. No. 4,473,331 issued to M. Wisecarver on Sep. 25, 1984; U.S. Pat. No. 4,669,934 issued to W. Wisecarver on Jun. 2, 1987; U.S. Pat. No. 4,781,499 issued to W. Wisecarver on Nov. 1, 1988; U.S. Pat. No. 5,028,185 issued to P. Shannon on Jul. 2, 1991; and U.S. Pat. No. 5,094,576 issued to C. Fredelius on Mar. 10, 1992. In the '934, '499 and '576 patents a rack-type gear is used in conjunction with a pinion gear having teeth only on a portion of the periphery. This construction limits the final adjustment of the total length to the extension provided by these gear components to about one inch. If total travel has initially been utilized, should the load restrainer become loose, the only source of length change is in the bar itself, with again adjusting the gear portions. Truck wall vibration can often exceed one inch. Other of the devices shown in the above-listed patents are useful only for light loads, such as those in a pickup truck. Most all utilize some form of spring that will not withstand hard usage.
A further load "lock" that is commonly utilized is essentially a ratcheting bumper jack attached to a rod. This, too, utilizes a spring element that has been found to fail after only a reasonable use time. For example, one trucking firm that utilizes such a unit has found that the average life of the load securing device is about ninety days. As will be understood, usage by a trucking firm imposes conditions of large vibrations, truck wall deformation, rough handling by users, etc., that contribute to early failure.
Accordingly, it is an object of the present invention to provide a rugged load securing device for holding loads in place within transport trucks.
It is another object of the present invention to provide a load securing device that has a wide range of final length adjustment after a gross length adjustment is made in the rod itself.
A further object of the present invention is to provide a load securing device that does not utilize springs or other elements of high failure potential such that the life is substantially extended.
Also, an object of the present invention is to provide a load securing device that is simple and inexpensive to construct but provides for extended operation without any maintenance.
These and other objects, advantages and features of the present invention will become apparent upon a consideration of the drawings forming a part hereof, together with a complete description thereof.